By USC do you mean LAC-USC Medical Center? You may already know this, but JIC, the hospital is not on or adjacent to the USC campus - it is on the Southeast edge of downtown Los Angeles (on State St,. near where I-5 and I-10 intersect) .

MDR is near LAX and Venice, not bad for UCLA, more problematic for USC (especially in traffic). I think that the CY on Olympic Boulevard in Century City is a great suggestion. To get to UCLA, take Olympic west to Westwood Blvd, hang a right, and head straight for the campus. Even better, on the day you go to County-USC, you could actually take Olympic eastbound all the way into Downtown LA and easily make your way over to County-USC.

Personal note: The dedicated nurses and doctors at the County-USC burn unit saved my older brother's life after he suffered a bad accident some thirty years ago.